Screen assembly for screening elastomeric material

Abstract

A screen assembly for mounting on the outlet end of an extruder for removing foreign particles from an elastomeric material being discharged from the extruder. The assembly includes a screen support member having a plurality of spaced elongated ribs formed integrally with or removably mounted on a surrounding member. The spaced ribs form a plurality of elongated slots therebetween which provide flow paths for the elastomeric material, and preferably are concavely-shaped in the direction of travel of the extruded material. A mesh screen formed of a high tensile strength, work hardened stainless steel wire cloth is formed complementary to the concavity of the ribs and is mounted in juxtaposition to the ribs for removing the foreign particles as the elastomeric material passes through the screen. The concavity of the ribs and formation of the elongated material flow paths, reduce the amount of back pressure created in the elastomeric material and reduces the bending and shear forces created on the ribs and surrounding support member.

We claim: 
     
       1. A screen assembly including: (a) a mesh screen adapted to be mounted adjacent a discharge outlet of an extruder for removing foreign particles from a material being discharged from the extruder;   (b) support means for supporting the mesh screen adjacent the discharge outlet of the extruder, said support means having a plurality of spaced elongated support ribs concavely-shaped in the flow direction of the material being discharged from the extruder forming a plurality of elongated slots therebetween for passage of the discharged material therethrough, with said screen being in juxtaposition to the ribs on the upstream side of the discharged material and being concavely-shaped complementary in curvature to the concavity of the support ribs; and   (c) means for mounting the support means and screen adjacent the discharge end of the extruder.   
     
     
       2. The assembly defined in claim 1 in which said screen is formed of a high strength, work-hardened stainless steel wire cloth. 
     
     
       3. The assembly defined in claim 1 in which the support means includes an outer annular ring with the ribs being formed integral therewith; and in which the concavely-shaped ribs form a slotted dome-shaped concave central portion. 
     
     
       4. The assembly defined in claim 3 in which the mesh screen is preformed concavely-shaped and is seated within the dome-shaped central portion of the support means. 
     
     
       5. The assembly defined in claim 3 in which the dome-shaped concave central portion is hemispherically-shaped. 
     
     
       6. The assembly defined in claim 1 in which the transverse thickness of the ribs is less than the transverse width of the elongated slots formed therebetween. 
     
     
       7. The assembly defined in claim 1 in which the support means includes a pair of spaced end clamping members; in which each of the ribs have spaced end mounting pads; and in which the ribs are individually removably mounted in a parallel spaced relationship by engagement of the end clamping members with the end mounting pads. 
     
     
       8. The assembly defined in claim 7 in which spacer plates are mounted between spaced pairs of the ribs to maintain said ribs in the parallel spaced relationship. 
     
     
       9. The assembly defined in claim 8 in which a hole is formed in each of the end mounting pads of the ribs and in the spacer plates; in which the holes are in transverse alignment with each other; and in which bolt means extends through said aligned holes for retaining said ribs and spacer plates with respect to a pair of spaced side support members. 
     
     
       10. The assembly defined in claim 8 in which each of the end clamping members is formed with a transversely extending undercut groove; and in which the rib mounting pads and spacer plates each have an anchoring projection formed thereon which seat in the undercut groove of the end clamp members to assist in anchoring said ribs and spacer plates with said end clamping members. 
     
     
       11. The assembly defined in claim 8 in which the mounting means includes an extrusion head having a converging extrusion outlet flow channel formed therein; and in which an extrusion die is mounted on the extrusion head in alignment with the outlet flow channel. 
     
     
       12. The assembly defined in claim 11 in which the extrusion head is formed with a pair of spaced transversely extending mounting channels; and in which the end clamping members are seated in said mounting channels. 
     
     
       13. The assembly defined in claim 7 in which the support means further includes a pair of spaced side clamping members extending transversely to the spaced end clamping members and forming a generally rectangular frame providing a rectangular opening therebetween; in which the ribs extend across said rectangular opening; in which the mounting means includes a plate having pairs of spaced mounting channels formed therein; and in which the end and side clamping members are seated in respective spaced pairs of mounting channels to assist in anchoring said clamping members on the mounting plate. 
     
     
       14. The assembly defined in claim 13 in which the support means further includes a pair of side support members assembled with the ribs and in clamping engagement with the side clamping members; in which screen retention grooves are formed in each of the side support members; and in which a ferrule is mounted in said retention grooves to assist in retaining an outer periphery of the mesh screen in clamped engagement between said side clamping members and side support members. 
     
     
       15. A screen assembly for removing foreign particles from a material being discharged from an outlet of an extruder including; a disc-shaped screen support member adapted to be mounted adjacent the discharge end of the extruder, said support member having an outer annular ring-like member and a central portion, said central portion containing a plurality of ribs formed integral with the outer annular ring and forming a plurality of elongated parallel slots, said ribs being in a parallel spaced relationship and are concavely curved in the direction of the material being discharged from the extruder and form a dome-shaped central portion and with the transverse thickness of each of the ribs being less than the transverse width of the intervening slots; and a mesh screen concavely-shaped complementary to the dome-shaped central portion of the support member and seated within said central portion. 
     
     
       16. The assembly defined in claim 15 in which the dome-shaped central portion is hemispherically-shaped. 
     
     
       17. In combination, an extruder and a screen assembly, said screen assembly including a mesh screen adapted to be mounted adjacent a discharge outlet of the extruder for removing foreign particles from an elastomeric material being discharged from the extruder, support means for supporting the mesh screen adjacent the discharge outlet of the extruder, said support means having a plurality of spaced elongated support ribs concavely-shaped in the flow direction of the material being discharged from the extruder forming a plurality of elongated slots therebetween for passage of the discharged material therethrough, with said screen being in juxtaposition to the ribs on the upstream side of the discharged material and being concavely-shaped complementary in curvature to the concavity of the support ribs, and means for mounting the support means and screen adjacent the discharge end of the extruder.